1. Field of the Invention
The present invention is related to a lithographic tool that increases multiple exposure throughput in ultra violet environments by switching multiple reticles during exposure.
2. Background Art
Lithography tools have been developed to allow smaller and smaller devices to be patterned on a wafer. Lithographic tools and methods are being developed that utilize multiple exposure. During multiple exposure, two or more reticles are imaged sequentially based on reticle swapping between imaging. Multiple exposure is particularly advantageous in extreme ultra violet (EUV) imaging to overcome undesirably low k1 imaging effects. In existing systems, the reticle swap time heavily impacts throughput because each reticle to be swapped must be transferred from ambient pressure to vacuum just before exposure. Unfortunately, there are no existing lithographic tools that perform multiple exposures and efficiently house multiple reticles at vacuum.
Therefore, what is needed is vacuum storage for holding two or more reticles, such that the vacuum storage is coupled to a vacuum chamber. This configuration would allow for fast reticle swap during multiple exposures, and hence throughput improvement.
Embodiments of the present invention provide a method including the steps of processing reticles in a vacuum processing section received from a vacuum input section, storing the reticles in a vacuum library, storing data correlating information generated during the processing step and a location of each one of the reticles stored in the vacuum library, and retrieving a requested reticle to be used for exposing a pattern on a wafer from the vacuum library based on the storing data step.
Other embodiments of the present invention provide a method comprising the steps of providing a central vacuum section having a robot. The method also includes the steps of coupling a vacuum input section to the central vacuum section, the vacuum input section receiving reticles before they are brought into the central vacuum section by the robot. The method also includes the steps of coupling a first vacuum holding section to the central vacuum section. The first vacuum holding section receives one reticle at a time from the robot. The method also includes coupling a second vacuum holding section to the central vacuum section via a valve. The second vacuum holding section simultaneously holding a predetermined amount of the reticles received through the valve from the robot. The method also includes coupling an exposure section to the central vacuum section. The exposure chamber receives reticles transported from one of the first or second vacuum holding section via the robot.
Still further embodiments of the present invention include a system including a central vacuum section and a robot positioned in the central vacuum section. The system also includes a pressure controlled input section that receives reticles before they are brought into the central vacuum section by the robot, a first holding section that holds one of the reticles at a time received from the robot, and a second holding section coupled to the central vacuum section that simultaneously holds a predetermined amount of the reticles received from the robot. The system also includes an exposure section that receives the reticles from the robot.
Still further embodiments of the present invention provide a method including the steps of indexing reticles before transferring the reticles to a vacuum input section, processing the reticles in a vacuum processing section that are received from the vacuum input section, storing the reticles in a vacuum library, indexing said stored reticles, and retrieving a requested reticle to be used for exposing a pattern on a wafer from the vacuum library based on said indexing steps.
Through the above embodiments, reticle swap time during multiple exposure is substantially reduced by having a plurality of reticles stored within the lithography tool at vacuum. This, in turn, decreases the costs of manufacturing semiconductors and solves imaging problems that occur in EUV environments.
Further embodiments, features, and advantages of the present inventions, as well as the structure and operation of the various embodiments of the present invention, are described in detail below with reference to the accompanying drawings.